1. Field of the Invention
The present invention relates to a liquid crystal display panel having a lenticular lens mounted on its display surface, and to a manufacturing method of the same.
2. Description of the Related Art
Recently, there have been active developments conducted on a display device which provides different images towards a plurality of viewpoints. For example, Japanese Unexamined Patent Publication 6-332354 (paragraphs 0070-0073, FIG. 10: Patent Document 1) discloses a display device which simultaneously provides different images for a plurality of observers located at different positions, and Japanese Unexamined Patent Publication 2005-208567 (paragraph 0101: Patent Document 2) discloses a display device which sends different images for left and right eyes of an observer for allowing the observer to recognize the images as a stereoscopic image. Both of those display devices utilize a lenticular lens comprises a plurality of semi-cylindrical lens which images provided for each direction are synthesized and images are distributed to corresponding directions.
FIG. 14 is a sectional view showing a structure of a liquid crystal display panel to which a lenticular lens as a independent part is loaded. The liquid crystal display panel shown in FIG. 14 is formed in a structure in which a thin-film transistor (referred to as TFT hereinafter) substrate 36 and a color filter substrate 30 (referred to as CF substrate hereinafter) are laminated via a seal member 32, and a twisted nematic (referred to as TN hereinafter) liquid crystal 34 is sealed between both substrates.
The TFT substrate 36 has, facing to a surface of the CF substrate 30 side, a thin-film element area 37 on which a TFT pixel switch array, signal lines, scanning lines, a pixel electrode, a TFT driving circuit, and the like are formed. An alignment film 39 on which rubbing processing has been done is printed on a part of the surface of the TFT substrate 36 facing to the CF substrate side 30 where the TN liquid crystal 34 is sealed, and a polarizing plate 38 is provided on the opposite-side surface.
In the meantime, the CF substrate 30 has, facing to the surface of the TFT substrate 36 side, a counter electrode forming layer 35 on which a counter electrode, a metal light-shielding film, and the like are formed. A CF layer 31 configured with a color layer, a black matrix, an overcoat layer, and the like is provided on a part of the surface on the TFT substrate 36 side where the TN liquid crystal 34 is sealed, and the alignment film 39 to which rubbing processing has been done is coated on the surface. Further, the polarizing plate 38 and a lenticular lens 33 are provided on the opposite-side surface of CF substrate 30.
However, since such liquid crystal display panel is formed by laminating the separately-formed lenticular lens 33 onto the CF substrate 30, there are some issues generated in terms of thermal expansion in parallax, increase in the weight, lack of long-term reliability in the laminated layers, etc. Japanese Unexamined Patent Publications 10-268247 (paragraphs 0049-0052, FIG. 2: Patent Document 3) and 2004-4745 (paragraphs 0107-0116, FIG. 1: Patent Document 4) disclose examples of techniques which can improve such issues. The techniques disclosed in Patent Document 3 and Patent Document 4 form a lens shape by performing wet etching on a glass substrate by using HF (hydrofluoric acid) solution. By applying such techniques, it is possible to form the lenticular lens shape on the surface of the CF substrate (glass substrate) in a unified manner.
However, unlike a quartz glass substrate formed only with SiO2, a normal glass substrate for a liquid crystal display panel contains oxides such as Al (Aluminum), Ba (Barium), Ca (calcium), Sr (Strontium) as impurities in addition to having SiO2. Thus, when performing wet etching process by using the HF solution, residuals such as AlF3, BaF2, CaF2, SrF2, and the like are generated and remained, which cause deterioration in the etching shape controllability. This results in lowering the yield rate of the liquid crystal display panels each having the lenticular-lens unified substrate.
In order to avoid influences of the residuals, Patent Document 3 discloses a glass substrate not containing Ba. However, as described above, the residual-forming impurity on the normal glass substrate used for the liquid crystal display panel is not only Ba. Further, the Ba-less glass is expensive so that the cost is increased.